A. Prior Art
Nonwoven fabrics have been known for some time. Nonwoven fabrics have been made from synthetic fibers such as the polyester and polypropylene fibers. Generally, these fabrics are produced by forming a web of fibers and applying an adhesive binder to the web to hold the fibers together and provide strength. In some instances (i.e., the spunbonding technique), synthetic polymers are extruded into filaments and directly formed into webs which selfbond to produce the final fabric. In other instances, the fibrous web is fluid rearranged and then resin binder is added to form a useful, coherent nonwoven fabric. See, for instance, Kalwaites, U.S. Pat. Nos. 2,862,251, 3,033,721, 3,193,436, and 3,769,659, and Griswold, U.S. Pat. Nos. 3,081,515 and 3,025,585. Still other nonwoven fabrics are made by forming a web of synthetic fibers and treating it with high-pressure jets to entangle the fibers and produce a strong fabric that does not require the addition of binder to be self-supporting and useful for many purposes. Such a technique is described by Evans in U.S. Pat. No. 3,485,706 and Canadian Pat. No. 791,925.
The prior art polyester fiber nonwoven fabrics suffer from one or more of the following problems: Adhesively bonded webs of textile polyester fibers require relatively large amounts of adhesive binder for most end uses to provide the fabric with adequate strength. The large amount of binder increases cost and can detract from the desirable textile-like properties of the fiber itself. The spunbonded type of product is expensive, and being of continuous extruded filaments, also has some limitations on its functional properties and its textile-like nature. For instance, spunbonded fabrics can be stiff and boardy in the higher weight range of products. The highly entangled fabrics of Evans have excellent fabric properties, but the Evans process requires a substantial capital investment and it uses large amounts of power. This invention provides a process and fabric product that eliminate many of the above-mentioned problems.
B. Objects Of The Invention
It is an object of the invention to provide a relatively economical process for producing strong, durable nonwoven fabrics having reduced binder content.
It is another object of the invention to provide a process for producing strong, durable nonwoven fabrics from polyester and/or polyolefin fibers.
It is a further object of the invention to provide strong, durable polyester and/or polyolefin nonwoven fabrics.
Still another object of the invention is to provide an economical process for producing strong, durable polyester and/or polyolefin nonwoven fabrics having reduced binder content.
These and other objects of the invention will be apparent from the following description of the invention.